The present invention relates to an automatic vertical blind controller with memory.
Vertical blinds have been widely used in home and office for easily adjusting indoor lighting from an outdoor lighting source. However, the conventional vertical blind, such as the manual/automatic vertical blind controller disclosed in the U.S. Pat. No. 4,956,588, has a lot of defects, as follows:
1. As shown in FIG. 5, a circuit diagram for an infrared receiver circuit disclosed in the above U.S. patent R5 and R6 are semi-adjustable carbon resistors for adjusting base voltage, and R1 and R2 are resistors for picking up overload signals from driving circuit ICs 53 and 54 in order to provide a voltage to a motor overload detection circuit (60). However, because R5 and R6 are adjustable, it is necessary to adjust their sensitivity in every use, which is not convenient, and the adjustment may therefore be inaccurate.
2. The driving circuit ICs 53 and 54 normally can withstand a current of about 1.5 Amp, but the d.c. motor (M1 or M2) may continue to run after the vertical blind reaches the end, and hence, overload will occur, which results in a increasing of current to the ICs 53 and 54, and consequently burning out of the ICs 53 and 54, or even fire.
3. The rail of the vertical blind will may become oxidized and will accumulated dust after prolonged use, resulting in larger friction on the rail, and consequently the load becomes greater. Taking this load into consideration, the maximum length of vertical blind applicable is usually about 2 to 3 meters. Hence, the prior art is not practical.